CorpWest SIP Trunking Service

SIP trunking connects your IP phone system to the outside world allowing incoming calls via a regular phone number and outgoing calls to other phone numbers. In a traditional phone system, each physical phone line from the local phone company could handle ONE call. that call could be either a call in or a call out. SIP trunking allows multiple calls in and out over your IP connection. The following will help explain the terms we use for incoming and outgoing calls and how we track and bill for those.

Concurrent Calls

SIP trunks are measured in concurrent calls. Simply put, that is the number of calls (both in and out) through our service at any one time. Calls made to or from our SBC (Session Border Controllers) to or from your PBX are considered a concurrent call. Calls made extension to extension on your PBX are not through our SBC and are not counted as concurrent calls.

SIP Origination

SIP Origination is the calls coming in to your PBX from the outside world via a phone number. CorpWest has local phone numbers available in all California local markets and soon the rest of the United States. We can either get you a new phone number or "port" your current phone number(s) over to our SIP service. For example, our phone number of 408-374-4655 is provided over SIP Origination to the PBX for CorpWest. There are no per minute fees or limits on these calls. We also offer origination of toll free calls. There is a per minute fee for toll free origination.

DID Numbers

DID Numbers are your telephone numbers (ie: 408-374-4655). You can have any number of DIDs pointed to your PBX. Some common uses for additional DIDs would be dedicated numbers for each person, numbers in other markets (ie: 925-855-0881), or numbers for special advertising campaigns. DIDs cost only $1 per month.

SIP Termination

SIP Termination is calls placed from your PBX to outside numbers. Local, long distance, and toll free calls are all treated the same. SIP termination calls are measured in minutes and rounded up to the next minute.


ServiceMonthly Fee
Concurrent Call (CC) $35.00 per Concurrent call
DID Number $1.00 per DID #
Addtl Origination Minutes
each CC incl. 300 minutes free
$0.025 per minute
Termination Minutes no charge
Toll Free Number $2.00 per toll free DID #
Toll Free
Origination Minutes
$0.05 per minute


Suppose you have 1 main line, 4 roll-over lines, and a fax line and are moving to a VOIP system. Instead of keeping those lines, you could keep just the fax line and move to SIP trunking with 5 concurrent calls and a single DID#. The monthly cost would be:

  • 5 Concurrent calls @$35
  • 1 DID# @ $1
  • Total: $176 per month
That would include unlimited incoming minutes and 1500 outgoing minutes - local or long distance. Additional lines can be added within minutes with no installation fees instead of days or weeks and additional equipment and fees with traditional lines.

Contact our sales department for a free comparison of your current phone bill to our SIP trunking plan and see how much money you might save.

All pricing is based on a 2 year commitment and subject to credit terms and conditions. See our SIP termination and origination agreement available from your sales person for important details and conditions.
CorpWest also offers extensive hosting and support plans starting as low as $99/month for your dedicated IP PBX server. Contact your salesperson for details.

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